Modern pneumatic particulate distribution systems, commonly referred to as air seeders, are used to distribute seed, fertilizer, or other particulate matter during various agricultural practices. Air seeders typically include an air cart and a tilling implement which are towed in tandem behind a tractor.
The air cart includes a frame riding upon wheels and tires, and one or more frame-mounted product tanks for holding granular product, such as seed, fertilizer, herbicide and/or other product. The product tanks are each connected to a product metering device which feeds the product into a pneumatic distribution system in a controlled manner. Typically various components within the product metering device(s) and/or pneumatic distribution system(s) are controlled by any of a variety of suitable electronic controls.
In general, the pneumatic distribution system functions to intake granular product from the metering device, transport it to the tilling implement, and then deliver the product to the field. In particular, the pneumatic distribution system includes a primary distribution manifold that intakes the product from the metering device and also an airflow from a centrifugal fan. The rotational speed of the centrifugal fan can be controlled by such electronic controls, as desired.
Controlling the rotational speed of the centrifugal fan influences a resultant airflow velocity within the pneumatic distribution system. Furthermore, the airflow velocity within the pneumatic distribution system can be influenced by, e.g., articulating baffles placed with the system that can be “opened” to provide relatively less system flow resistance or “closed” to provide relatively more system flow resistance. Typically, such baffles are placed upstream in the pneumatic distribution system; in other words, between the centrifugal fan and the primary distribution manifold.
The primary distribution manifold intakes an airflow delivered by the centrifugal fan and product delivered by the metering device into a common chamber, whereby the product is introduced into and becomes entrained in the airflow. The primary distribution manifold divides the airflow(s) and directs the airflow and the entrained product through multiple air cart air lines. The air cart air lines attach to a series of secondary distribution manifolds, commonly referred to as “headers,” typically at the tilling implement. The headers further distribute the airflow and entrained product through multiple implement distribution air lines, to multiple ground openers on the tilling implement. At this point, the air bleeds off through an air vent, whereby the product falls by way of gravity to the ground or seedbed. Optionally, the product falls by way of gravity into a planting unit for singulation prior to seedbed or furrow delivery.
The use of precision-type agricultural practices is becoming increasingly popular, as is the desire to improve the operating efficiency of agricultural equipment. In light of precision-type agricultural practices and desire to improve efficiency, known air seeders exhibit certain limitations. For example, at times during use, various components of the pneumatic distribution system can encounter flow resistances and corresponding operating pressures and flow velocities that are outside of a desired or optimal range. Such non-desired operating parameters can be effectuated at least in part by, e.g., (i) the distance that the airflow and entrained product travels within the pneumatic distribution system, (ii) the numerous mechanical interfaces that the airflow and entrained product encounters during system travel, e.g., couplers, baffles, or other structures within manifolds, arcuate lengths of air line sidewalls, (iii) wear and maintenance status of components within the pneumatic distribution system, and (iv) various other factors and conditions.
Such occurrences of non-desired operating air line resistances, pressures, and flow velocities typically include non-equal magnitudes of airflow velocity, or airflow velocity differentials, between the various air lines within the air distribution system. As a result, the integrity and consistency of the seeding volume as a function of time and/or seed distribution pattern upon the ground, field, seedbed, or furrow can be compromised. Correspondingly, overseeding, underseeding, or inconsistent seeding distribution patterns can result.
Airflow velocity differentials typically result from at least one air line having a relatively lower airflow resistance value, and correspondingly a relatively higher or excessive airflow velocity value, as compared to the other air lines within the pneumatic distribution system. This excessive airflow velocity requires higher static air line pressure(s) to transmit, which in turn requires more power input to achieve, potentially wasting energy in the process. Furthermore, the excessive airflow velocity causes excessive abrasive wear to the inner surfaces of the air line. Namely, the airflow entrained product collides with such inner surfaces at a corresponding greater velocity, thus with more force and greater frequency, thereby causing more abrasive damage. Conversely, a minimum airflow velocity must be maintained to suitably entrain and transport the product through the air seeder, whereby airflow velocities falling below the minimum can result in plugging, clogging, or accumulation of product within the pneumatic delivery system.
Previous attempts have been made to equalize the pressures and airflow velocities between various air lines in seeders, to decrease the magnitude of the airflow velocity differential. For example, devices and corresponding methods have been previously provided for monitoring particle velocity of the airflow entrained product and controlling a flow restricting damper or the rotational velocity of the centrifugal fan in accordance therewith, to mitigate the airflow velocity differential. While such systems have been adequate, they require sophisticated electronics and controls, and are relatively expensive to produce and maintain.